disable FormGroup by using Validators

Question

I had formArray checkbox on my checkboxForm, I need to disabled button submit if no checkbox are checked, I had implement custom validator

Answer 1

When you are initializing the form in the constructor add the validator to the formarray first.Then after you receive the data call the addCheckboxes method.

form: FormGroup;
receivedSummons = [];

constructor(private formBuilder: FormBuilder) {
   this.checkboxForm = this.formBuilder.group({
     receivedSummons: new FormArray([], minSelectedCheckboxes(1))
   });

   of(this.someMethodWhichReturnReceivedSummons()).subscribe(receivedSummons => {
      this.receivedSummons = receivedSummons;
      this.addCheckboxes();
   });
}

In the addCheckboxes

private addCheckboxes() {
    this.receivedSummons.map((o, i) => {
      const control = new FormControl(i === 0); // if first item set to true, else false
      (this.form.controls.receivedSummons as FormArray).push(control);
    });
}